Image projection system with adjustable cursor brightness

ABSTRACT

An image projection system is disclosed. The system comprises a projector, a user input device and a computing device. The micro-mirror based projector projects an image including a cursor on a display plane. The present invention discloses various embodiments for the system and method of adjusting the brightness of the cursor to improve effects of a presentation. According to one embodiment, the brightness of the cursor is adjusted by modifying the on/off time ratio of the mirrors by which the cursor is formed. According to another embodiment, the projector comprises a first and a second micro-mirror array. The second array is dedicated for projecting the cursor image. The brightness of the cursor may be adjusted by changing the number of micro-mirrors by which the cursor is formed from the second array.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND

1. Field of Invention

This invention relates to an image projection system, specifically to animage projection system with adjustable cursor brightness.

2. Description of Prior Art

When making a presentation for a lecture or the like using amicro-mirror based projector, a laser pointer, which indicates a pointon a screen by projecting a laser beam is often used. A laser pointer ofthis type has, however, the following disadvantages. Shake greatly andadversely influences the pointing operation, thereby making the pointunstable. A laser beam may be erroneously projected to be hazardouslyincident on eyes of audience. In addition, the shape of point is limitedto simple shapes such as a circle and a line, which can not satisfy thedemand for changing the shape of the point according to the user'spreference. Furthermore, the brightness of the point cannot be adjusted.

Conventional computer pointing devices such as a mouse, a trackball, ora touchpad are also known in the prior art. The pointing devices allow auser to control the operation of a cursor on a computer screen andtherefore a cursor on a large display plane in a synchronized manner fora presentation system comprising a projector and a computer. Mostpointing devices are connected to a computer through a wire. This limitsthe use of such devices as a control and presentation tool because thewire limits their range of movement and flexibility of connections.

Wireless pointing devices have become available in recent years. Thedevices allow for greater range of movement and connection flexibility.The wireless pointing devices are preferred for the projector becausethe lack of a wire or a cord allows a user to freely move about whilecontinuing to maintain control of a cursor on the display plane.

However, a problem with the computer based presentation system with acursor as the point is that the cursor has the same brightness as theprojected image. Audiences may encounter difficulties in capturing thecursor's position on the display plane.

It is therefore desirable to have a computer based presentation systemwith adjustable cursor brightness, in particularly, with brighter cursorto enable the audiences to capture the movement and position of thecursor easily.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an imageprojection system with adjustable cursor characteristics, inparticularly the cursor brightness to improve experience of thepresenter and the audience.

In one embodiment of the present invention, the brightness of the cursoris adjusted by modifying the on/off time ratio of selected micro-mirrorsby which the light beams reflected form pixels of the cursor image.

In another embodiment of the present invention, the image projectorcomprises a first micro-mirror array for projecting an image such as aslide for a presentation and a second micro-mirror array for projectingan image of a cursor. The projected image of the cursor is formed by aplurality of pixels. The brightness of the cursor may be adjusted byselecting an appropriate number of micro-mirrors from the second array.More mirrors are selected, brighter the cursor. The second array shouldhave a sufficiently large number of mirrors to allow the user to adjustthe brightness in a desired range. The micro-mirror arrays arecontrolled by a controller. The controller translates the user'sinstructions from the input device into a series of controlling signalsfor the controller to control the operation of the arrays. The first andthe second micro-mirror arrays may be integrated into a single chip.

In yet another embodiment, the methods of modifying the on/off timeratio of the mirrors and the one of using the second micro-mirror arraymay be combined to deliver a cursor with adjustable brightness.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsvarious embodiments, and the advantages thereof, reference is now madeto the following description taken in conjunction with the accompanyingdrawings.

FIG. 1A is a schematic diagram of an exemplary projector according toone embodiment of the present invention. The brightness of the cursor isadjusted by modifying the on/off time ratio of the micro-mirrors bywhich the reflected light beams form the image of the cursor.

FIG. 1B is a schematic diagram of an exemplary projector according toanother embodiment of the present invention. The brightness of thecursor is adjusted by selecting an appropriated number of micro-mirrorsfrom the second micro-mirror array to form the image of the cursor.

FIG. 2 is a schematic illustration that the first and the secondmicro-mirror arrays are integrated in a single chip in an exemplarycase.

FIG. 3A is a schematic functional block diagram of an image projectionsystem in one embodiment that the user input device is connected to thecomputing device.

FIG. 3B is a schematic functional block diagram of an image projectionsystem in another embodiment that the user input device is connected tothe projector directly.

FIG. 4 is a flow diagram depicting steps of operations of the imageprojection system in accordance with one embodiment of the presentinvention that the brightness of the cursor is adjusted by modifying theon/off time ratio of the micro-mirrors by which the reflected lightbeams form the cursor.

FIG. 5 is a schematic diagram of the user selectable interface for thecharacteristics of the cursor.

FIG. 6 is a flow diagram depicting steps of operations of the imageprojection system in accordance with another embodiment of the presentinvention that the brightness of the cursor is adjusted by selecting anappropriate number of micro-mirrors from the second array.

FIG. 7 is a flow diagram depicting steps of operations of the imageprojection system in accordance with yet another embodiment of thepresent invention that the brightness of the cursor is adjusted bymodifying on/off time ratio of the selected number of micro-mirrors fromthe second array.

FIG. 8 is a flow diagram depicting steps of operations of the imageprojection system in accordance with yet another embodiment of thepresent invention that the user input device is connected through thecomputing device.

DETAILED DESCRIPTION

The present invention will now be described in detail with references toa few preferred embodiments thereof as illustrated in the accompanyingdrawings. In the following description, numerous specific details areset forth in order to provide a thorough understanding of the presentinvention. It will be apparent, however, to one skilled in the art, thatthe present invention may be practiced without some or all of thesespecific details. In other instances, well known process steps have notbeen described in detail in order not to unnecessarily obscure thepresent invention.

The present invention is based upon a micro-mirror array device orDigital Light Processing (DLP). DLP is a trademark owned by TexasInstruments, Dallas, Tex., representing a technology used in projectorsand video projectors. It was originally developed by Larry Hornbeck ofTexas Instruments. In DLP projectors, the image is created bymicroscopically small mirrors laid out in a matrix on a semiconductorchip, known as a Digital Micro-mirror Device (DMD). Each mirrorrepresents one or more pixels in the projected image. 800×600, 1024×768,1280×720, and 1920×1090 (HDTV) matrices are common DMD sizes. Thesemirrors can be repositioned rapidly to reflect light either through thelens or on to a heat-sink.

Rapidly toggling the mirror between these two orientations (essentiallyon and off) produces grayscales, controlled by the on/off time ratio.

One of the methods by which DLP projection systems create a color imageis by a single DLP chip approach. Colors are either produced by placinga color wheel between the lamp and the DLP chip or by using individuallight sources to produce primary colors, LED's for example. The colorwheel is divided into multiple sectors: the primary colors: red, greenand blue, and in many cases secondary colors.

The DLP chip is synchronized with the rotating motion of the color wheelso that the red component is displayed on the DMD when the red sectionof the color wheel is in front of the lamp. The same is true for thegreen, blue and other sections. The colors are thus displayedsequentially at a sufficient high rate that the observer sees acomposite “full color” image.

The main light source used on micro-mirror or DLP-based projector isbased on a replaceable high-pressure mercury-vapor metal halide arc lampunit (containing a quartz arc tube, reflector, electrical connections,and sometimes a quartz/glass shield), while in some newer DLP projectorshigh power LED's are used as a source of illumination.

The brightness of a projected image can be adjusted by modifying theon/off time ratio of the mirrors. According to one embodiment of thepresent invention, the brightness of a cursor image may be adjusted bymodifying the on/off time ratio of the micro-mirrors by which the cursorimage is formed through the reflection of the light beams.

The brightness of a projected image can also be adjusted by directingmore or less light beams reflected from the micro-mirrors to form theimage of the cursor. A second micro-mirror array may be utilized in adedicated manner to project the image of the cursor. The number ofmirrors in the second array needs to be sufficiently high to allow thebrightness of the cursor be adjusted in a desired range.

The brightness of a projected image can further be adjusted by combiningthe modification of the on/off time and the selection of an appropriatenumber of mirrors from a dedicated array.

FIG. 1A is a schematic diagram of an exemplary projector 100 accordingto one embodiment of the present invention. The projector 100 comprisesa light source 102, a micro-mirror array 104, and a controller 106. Thelight source 102 may be a replaceable high-pressure mercury-vapor metalhalide arc lamp unit with a color wheel. The light source 102 may alsobe a plurality of high power LED's. The micro-mirror array 104 may be aDMD or DLP. The controller 106 may be a data processor pertaining tocontrol the operations of the micro-mirror array and the projector. Theprojector 100 further comprises an optical unit such as lens fordirecting light beams reflected by the micro-mirror array 104 from thelight source 102 to a display plane. The communication unit 110 is forconnecting the projector 100 with a computing device and/or a user inputdevice. The communication unit 110 may be a wired connection such as forexample an IEEE 1394 type of connection (FIREWIRE) or a Universal SerialBus type of connection (USB). The communication unit 110 may also be awireless communication transceiver such as a Bluetooth, WiFi, and ZigBeetype of transceiver. A power supply 112 supplies power for theoperations of the projector. The projector 100 further comprises acursor control unit 114. 114 may be implemented as a piece of software.114 may also be implemented as a piece of hardware or a combination ofsoftware and hardware. 114 may be a part of the controller 106.

After receiving the user's selections of the characteristics (e.g.shape, size, color, and brightness) of the cursor from a user interfaceat a setup phase of the projector, the cursor control unit 114translates the selections into a set of parameters for controlling theoperations of the micro-mirrors by which the cursor is formed. When auser operates a user input device to move the cursor to a desiredposition on the display plane, a coordinate of the cursor is determinedby the controller 106. Micro-mirrors forming the cursor imagecorresponding to the coordinate are determined. The predeterminedcontrol parameters such as the on/off time ratio are applied to eachmirror forming the cursor to project a desired image. When the cursor ismoving on the display plane, the above mentioned operation is repeatedin a rapid manner. The user and the audiences will only observe a movingcursor with desired characteristics.

FIG. 1B is a schematic diagram of an exemplary projector 101 accordingto another embodiment of the present invention. The projector 101comprises a conventional DLP based projector 103 and various units asillustrated in an add-on module 105. The embodiment is characterized bythat the projector 101 includes a first micro-mirror array 104 and asecond micro-mirror array 114. The second micro-mirror array 114 isdedicated to generate the cursor image. The brightness of the cursorimage can be increased significantly by directing more light beamsreflected by more micro-mirrors than normally required to form thecursor image. The operation of 114 is controlled by the secondcontroller 116. The first and the second micro-mirror array 104/114 maybe integrated in a single chip. The cost by adding a fraction of moremicro-mirrors in the same chip is low based upon the integrated circuitsbased micro-machining process. The first and second controllers 106/116may be in an integrated form. They may also be separate units.

The second communication unit 118 is used to connect the projector witha user input device. 118 may be a part of wired connection such as theFIREWIRE or the USB type of connection. A wired connection, however,limits the movement of the user (presenter) within a range defined bythe length of the connecting cable. A wireless connection by, forexample, the Bluetooth transceiver may provide more flexibility for theuser.

FIG. 2 is a schematic diagram that the first and the second micro-mirrorarrays are integrated in a single chip in an exemplary case. Themicro-mirrors from the second array may be grouped together asillustrated in the figure. It is, however, not necessary to arrange themirrors in such a manner. The mirrors from the second array may bearranged in other manners as appropriated. For example, the mirrors fromthe second array may be divided into four subgroups and be placed atfour different corners of the first array.

FIG. 3A is a schematic functional block diagram of an image projectionsystem according to one embodiment. The projection system 300 comprisesa projector 302, a display 304, a computing device 306 and a user inputdevice 308. The computing device 306 may be a general purpose computer.The computing device 306 comprises a display screen 310. The user inputdevice 308 may be a mouse of the computer. The mouse may be connected tothe computer in a wired manner or in a wireless manner as known in theart. After the computing device 306 is connected to the projector 302,the movement of the cursor on the display 304 and the movement of thecursor on the display screen 310 of the computing device 306 aresynchronized. The user can control the movement of the cursor on thedisplay 304 by the use of the input device 308.

FIG. 3B is a schematic functional block diagram of an image projectionsystem in another embodiment. The image projection system 301 comprisesthe projector 302, the display 304, the computing device 306 and theuser input device 308. The user input device 308 is connected to theprojector 302 directly according to the embodiment. The projector 302may include a wireless communication unit. 308 may be a wireless mousein an exemplary embodiment. The advantage of the present embodiment isthat the user input device 308 is always connected to the projector evenwhen the computing device 306 is replaced by a different one owned by adifferent presenter. When the computing device 306 is connected to theprojector 302, the movement of the cursor on the display screen 310 ofthe computing device 306 and the movement of the cursor on the display304 are synchronized.

FIG. 4 is a flow diagram depicting steps of operations of the imageprojection system 301. Process 400 starts with step 402 that theprojector 302 is switched on by the user. The user input device 308 isconnected to the projector 302 in step 404. A preliminary (or default)cursor image accompanying with a user selectable interface is thendisplayed on the display 304 in step 406. An exemplary user interface isillustrated in FIG. 5. The characteristics of the cursor include itsshape, size, color and brightness. C1 to C4 in the figure stands fordifferent colors. The user can select the desired characteristics bymoving the cursor to the right position and actuating the input device308 to make the selection. The user's selections are received by theprojector 302 in step 408. The micro-mirrors by which the cursor isformed is determined in step 410 based upon the shape and size of thecursor selected by the user. The color and the brightness of the cursoris determined by the on/off time ratio for each micro-mirror and foreach primary and each secondary color if it is used. An updated cursoris displayed in step 412. It should be noted that steps from 408 to 412may be repeated until a desired cursor image is established. After thecomputing device 306 is connected to the projector 302 in step 414, animage such as a slide is delivered by the computing device 306 to theprojector 302 and, consequently on the display 304 in step 416. The usercan then move the cursor with desired characteristics on the display asa point.

FIG. 6 is a flow diagram depicting steps of operations of the imageprojection system 301 according to the embodiment that the projector 302comprising the first and the second micro-mirror arrays 104/114. Thesecond micro-array 114 is dedicated to project the cursor image. Process600 starts with step 602 that the projector 302 is switched on by theuser. The user input device 308 is connected to the projector 302 instep 604. A preliminary (or default) cursor image accompanying with auser selectable interface is then displayed on the display 304 in step606. The user's selections are received by the projector 302 in step608. The number of micro-mirrors by which the cursor is formed isdetermined in step 610 based upon shape, size and brightness of thecursor selected by the user. The color of the cursor is determined bycontrolling the on/off time ratio for each primary and each secondarycolor if it is used. The brightness of the cursor is changeabledepending on the number of micro-mirror selected from the second array114. More micro-mirrors from the second array are selected, brighter thecursor. An updated cursor is displayed in step 612. Steps from 608 to612 may be repeated by the user until a satisfactory cursor image isdisplayed. After the computing device 306 is connected to the projector302 in step 614, an image such as a slide is delivered by the computingdevice 306 to the projector 302 and, consequently on the display 304 instep 616.

FIG. 7 is a flow diagram depicting steps of operations of the imageprojection system 301 according to the embodiment that the projector 302comprising the first and the second micro-mirror arrays 104/114.Further, the brightness of the cursor image may be adjusted by selectingthe number of micro-mirror by which the cursor is formed and also bymodifying the on/off time ratio for each selected mirror. The secondmicro-mirror array 114 is dedicated to project the cursor image. Process700 starts with step 702 that the projector 302 is switched on by theuser. The user input device 308 is connected to the projector 302 instep 704. A preliminary (or default) cursor accompanying with a userselectable interface is then displayed on the display 304 in step 706.The user's selections are received by the projector 302 in step 708. Thenumber of micro-mirrors from the second array 114 is determined in step710 based upon the user selected shape, size and brightness of thecursor. The color of the cursor is determined by controlling the on/offtime ratio for each primary and each secondary color if it is used. Thebrightness of the cursor is changeable depending on the number ofmicro-mirror selected from the second array 114. The brightness of thecursor can be further modified by controlling the on/off time ratio ofeach selected micro-mirror from the second array. An updated cursor isdisplayed in step 712. Steps from 708 to 712 may be repeated until asatisfactory cursor image is displayed. After the computing device 306is connected to the projector 302 in step 714, an image such as a slideis delivered by the computing device 306 to the projector 302 and,consequently on the display 304 in step 716.

FIG. 8 is a flow diagram depicting steps of operations of the imageprojection system 300 (the user input device 308 is connected to thecomputing device 306). Process 800 starts with step 802 that theprojector 302 is switched on by the user. The computing device 306 isconnected to the projector 302 in step 804. The movement of the cursoron the display screen 310 of the computing device 306 is synchronized instep 806 with the movement of the cursor on the display 304. Apreliminary (or default) cursor accompanying with a user selectableinterface is then displayed on the display 304 in step 808. The user'sselections are received by the projector 302 in step 810. The number ofmicro-mirrors from the second array 114 by which the cursor is formed isdetermined in step 812 based upon shape, size and brightness of thecursor selected by the user. The color of the cursor is determined bycontrolling the on/off time ratio for each primary color and eachsecondary color if it is used. The brightness of the cursor ischangeable depending on the number of micro-mirror selected from thesecond array 114. The brightness of the cursor can be further modifiedby controlling the on/off time ratio of each selected micro-mirror. Anupdated cursor is displayed in step 814. Steps 810 to 814 may berepeated until a satisfactory cursor image is displayed. An image suchas a slide is delivered by the computing device 306 to the projector 302and, consequently on the display 304 in step 816.

1. An image projection system comprising: (a) a projector including afirst micro-mirror array and a second micro-mirror array on a singlemicro-chip; and (b) an input device wherein said first micro-mirrorarray is used for projecting an image on a display plane and said secondmicro-mirror array is used exclusively for projecting a cursor imageoverlapping the image.
 2. The system as recited in claim 1, wherein saidprojector further comprising a light source and a communication unit. 3.The system as recited in claim 2, wherein said communication unitconforms to a standard including an IEEE 1394 type of connector or aUniversal Serial Bus type of connector.
 4. The system as recited inclaim 2, wherein said communication unit conforms to a standard or acombination of standards from the following group: (a) ZigBee (IEEE802.15.4 and its amendments); (b) Bluetooth (IEEE 802.11 b and itsamendments); and (c) WiFi (IEEE 802.11 and its amendments).
 5. Thesystem as recited in claim 1, wherein the cursor image furthercomprising a plurality of pixels formed from reflected light beams by agroup of micro-mirrors selected from the second micro-mirror array. 6.The system as recited in claim 5, wherein brightness of the cursor imageis adjusted by adding or reducing number of selected micro-mirrors fromthe second micro-mirror array by the projector.
 7. The system as recitedin claim 1, wherein said system further comprising a computing device.8. The system as recited in claim 7, wherein said computing devicefurther comprising a user interface for receiving the user's inputs foradjusting the brightness of the cursor image through the user inputdevice.
 9. A method of adjusting brightness of a cursor image on adisplay plane of a projection system comprising a projector including afirst micro-mirror array and a second micro-mirror array, a user inputdevice and a computing device, the method comprising: (a) connecting theuser input device to the projector; (b) displaying a plurality of userselectable items including brightness of the cursor image; (c) receivingthe user's selection through the input device; and (d) adjusting thebrightness of the cursor image by changing the number of selectedmicro-mirrors from the second micro-mirror array by which the reflectedlight beams form pixels of the cursor image, wherein said firstmicro-mirror array and said second micro-mirror array are on a singlemicro-chip, wherein said second micro-mirror array is used forprojecting the cursor image exclusively.
 10. The method as recited inclaim 9, wherein said method further comprising connecting the userinput device to the projector through the computing device.
 11. Themethod as recited in claim 9, wherein said first micro-mirror array isused for projecting an image based upon a data file transmitted from thecomputing device.
 12. A method of projecting an image and a cursor imageon a display plane comprising: (a) displaying the image on the displayplane by a first micro-mirror array; (b) displaying the cursor imageoverlapping the image on the display plane by a second micro-mirrorarray; and (c) adjusting by a controller brightness of the cursor imageby adjusting number of micro-mirrors selected from said secondmicro-mirror array, wherein said first micro-mirror array and saidsecond micro-mirror array are on a single micro-chip, wherein saidsecond micro-mirror array is used for projecting the cursor imageexclusively.
 13. The method as recited in claim 12, wherein said methodfurther comprising determining by the controller a on/off time ratio foreach of the selected micro mirrors in said second micro-mirror array tomeet brightness requirements based on the user's inputs from the inputdevice.
 14. The method as recited in claim 12, wherein said methodfurther comprising determining a coordinate of the cursor image on thedisplay plane based upon the user's inputs from the input device. 15.The method as recited in claim 12, wherein said method furthercomprising receiving the user's inputs by displaying a plurality ofuser's selectable items for the cursor's characteristics on the displayplane at a setup phase of projector operation.
 16. The method as recitedin claim 15, wherein said cursor's characteristics further including ashape of the cursor image.
 17. The method as recited in claim 15,wherein said cursor's characteristics further including a color of thecursor image.
 18. The method as recited in claim 15, wherein saidcursor's characteristics further including a size of the cursor image.19. The method as recited in claim 12, wherein said method furthercomprising connecting the input device to the projector through awireless communication link.
 20. The method as recited in claim 12,wherein said method further comprising connecting the projector to acomputing device.